Display screen or a portion thereof with a graphical user interface



The sole FIGURE is a front view of a display screen or a portion thereof with a graphical user interface, showing our new design.

The short dash-dash broken lines showing text within the FIGURE illustrate portions of the graphical user interface that form no part of the claimed design. The short dash-dash broken line showing of the display screen forms no part of the claimed design. The dot-dot-dash and dot-dash broken lines represent boundaries of the claimed design and form no part of the claimed design. The portions of the graphical user interface that are shown with higher opacity represent portions of the display screen or portion thereof with graphical user interface that form no part of the claimed design. 

CLAIM The ornamental design for a display screen or a portion thereof with a graphical user interface, as shown and described. 